Objectives: To characterize the specific autonomic disturbances underlying the cold-induced sweating syndrome (CISS), and to describe a novel genetic variant of this rare recessive disorder. The two not previously reported patients had similar dysmorphic features: abnormal facial appearance, high arched palate, low set rotated ears, flexion deformities of elbows and fingers and scoliosis. Most noticeable were their paradoxical sweat responses: cold ambient temperature induced a profuse sweating over the face, arms and trunk but not over the lower limbs; while in the heat very little sweating occurred primarily on the legs. Testing of autonomic functions demonstrated normal cardiovascular reflexes and postganglionic sympathetic efferent functions. Sural nerve morphology and number of unmyelinated fibers was normal and skin biopsies showed normal appearing eccrine sweat glands. MRI scans revealed no structural brain abnormalities. Oral clonidine, prescribed in one patient, completely suppressed cold-induced sweating. Observed clinical features matched those of two sisters reported from Israel and of two brothers reported from Norway. All six cases presented a similar phenotype. The Norwegian, Israeli and Canadian cases were homozygous or compound heterozygous, respectively, for mutations in the CRLF1 gene on chromosome 19p12 (CISS1). The Australian case, however, had no pathogenic sequence variants in the CRLF1 gene, but was compound heterozygous for mutations in the CLCF1 gene on chromosome 11q13.3 (CISS2).
Conclusion: The rare cold-induced sweating syndrome is genetically heterogeneous and is probably caused by central and peripheral impairment of sudomotor functions. This is the first detailed report on the clinical consequences of mutations in the CLCF1 gene in humans. Directions for medical therapies are outlined to achieve long term symptom control.